Lecture 1: Cardiovascular & Renal Adaptations in Pregnancy Flashcards

1
Q

What are adaptations required for in pregnancy?

A

Increase CO and BV - maintain uteroplacental perfusion and maintain metal demands

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2
Q

How long is human pregnancy (from last menstrual period and fertilisation)?

A

280 days (40 weeks)

266 days (38 weeks)

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3
Q

What are the physiologic adaptations to pregnancy?

A

Hyperdynamic, hypermetabolic, hypervolemic, hypercoaguable, low resistance, compensatory respiratory alkalemia, diabetogenic

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4
Q

What is the ideal weight gain in pregnancy and when does it occur?

A

10-13kg, with 1-2kg in first trimester and 1-2kg/month in the 2nd and 3rd trimesters

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5
Q

Why is there extensive cardiac and resp work during pregnancy?

A

Additional breast tissue and uterine muscle are major contributors of increase in cardiac and resp work

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6
Q

What is the importance of glucose in pregnancy?

A

Major energy source for fetal and placental growth

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7
Q

When does maternal hyperglycaemia occur?

A

Late gestation

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8
Q

Why is there increased insulin synthesis and secretion?

A

Increased beta cell division and size

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9
Q

How much blood is lost in delivery?

A

500-600mL vaginal

800-1200mL caeserean

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10
Q

When should blood volume increase?

A

During pregnancy to accommodate for later loss of blood

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11
Q

What is the % increase of BV and when does it occur?

A

30-50% - begins at 6 weeks and peaks at 32 weeks

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12
Q

What is the % increase in plasma volume?

A

40-50%

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13
Q

What is the % increase in red cells mass and when does it occur?

A

25-30% – begins at 10 weeks and continues until term

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14
Q

Why does red cell mass increase?

A

Increased erythropoietin and red blood cell production

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15
Q

Why doe physiological anaemia and hemodilution occur?

A

Increase in blood volume exceeds increase in red blood cells

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16
Q

What is the % increase of white blood cells ad when does it occur?

A

25-30% - increase in 1st trimester and plateau in 2nd and 3rd

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17
Q

How does the number of total plasma proteins change?

A

Reduced albumin due to increased blood volume– 1st trimester – changes made contribute to propensity of oedema

18
Q

What is the % increase of total serum lipids?

A

40-60%

19
Q

What is the % of increase in cholesterol and why is this important?

A

40% - it is an important precursor for oestrogen and progesterone

20
Q

What are the changes in CV functioning?

A

Increased CO by 30-50%

  • Increased SV from 8 weeks
  • Increased HR from 5 weeks
  • Increased fluid retention/oedema
21
Q

What are the changes to BP in pregnancy and when do they occur?

A

Reduced BP – lowers in 1st trimester and is lowest at 24-32 weeks and returns to normal by term

22
Q

Is systolic or diastolic BP lower and why?

A

Diastolic pressure reduced more than systolic due to progesterone and relaxin reducing vascular resistance, blood being directed to placenta and refractory (protective) increases in renin and Ang II

23
Q

What happens to volume sensors in the kidney during pregnancy?

A

Reset

24
Q

What is the % increase of renal blood flow in pregnancy?

A

40-80%

25
Q

What is the increase in GFR in pregnancy?

A

30-50%

26
Q

How does kidney size change during pregnancy?

A

Increase by 1m due to increased renal blood flow and glomerular hypertrophy

27
Q

What does increased renal blood flow and GFR result in?

A

Increased filtration of water and solutes – increased urine flow and volume. However, renal tubules retain sodium and water to maintain blood/plasma volume expansion

28
Q

What does blood volume increase to?

A

7L

29
Q

When is plasma osmolality reduced?

A

By week 5 of pregnancy - 10mosmol/kg lower than preconception values by week 10

30
Q

How does the fluid relate to the foetus function in utero?

A

Foetus surrounded by fluid - not breathing oxygen, receiving it from mother via placenta. Foetus urinates in utero but don’t want to release toxins into fluid that baby swallows - placenta and mother act as foetal kidneys to filter toxins from womb as kidneys develop. Fluid develops GIT but has no nutritional value - placenta provides nutrition from mother. If these adaptations don’t happen adequately and alter placental function these actions will be compromised

31
Q

How is oxygen delivered to the baby?

A

Umbilical vein takes oxygenated blood to baby and umbilical arteries take deoxygenated blood away

32
Q

How does the placenta avoid problems with vasoconstriction?

A

Blood lakes

33
Q

What is the blood flow to the lungs in utero?

A

Less than 10%

34
Q

Where is oxygen saturation lowest and highest in the foetus?

A

Abdominal IVC and umbilical vein

35
Q

Does the foetus have high or low PO2 and haemoglobin levels?

A

Low PO2 and high haemoglobin

36
Q

Why is oxygen consumption higher in foetus?

A

Lower oxygen saturation but higher oxygen delivery and flow

37
Q

What are the four shunts for blood in the foetus?

A
  • Ductus Venosus: abdominal umbilical vein to IVC, streamlines blood flow to atria
  • Foramen Ovale: right atrium to left atrium
  • Dutus Arteriosus: Right ventricle, pulmonary artery to descending aorta, avoid blood perfusion to lungs
  • Umbilical circulation – 1 vein brings oxygenation blood from placenta to fetus and 2 arteries remove deoxygenated blood
38
Q

Why does ductus vernosus close?

A

Not being used or demanded (probably flow mediated) – closed 1-3 weeks after birth and later in premature babies (trigger unknown)

39
Q

Why does foramen ovale close?

A

Pressure change due to airflow when breathing

40
Q

Why does ductus arteriosus close?

A

Closes two days after birth due to oxygen mediated inhibition